A high-voltage direct-current circuit breaker branch short-circuit breaking test loop and method

Abstract

This invention discloses a short-circuit breaking test circuit and method for a high-voltage DC circuit breaker's breaking branch, belonging to the field of high-voltage testing technology. It includes a current source circuit, a converter branch, and a voltage source circuit. The current source circuit consists of an impulse generator G, a closing switch MK, an auxiliary switch FK, a current-limiting reactor L, and a short-circuit test transformer T from a high-power test station. The converter branch is a pulse capacitor C. S High-frequency reactor L S It consists of a converter switch S. The voltage source circuit consists of a pulse main capacitor C. h High-voltage ignition ball gap Gap, and frequency modulation reactor L h Composition. This circuit can be used to assess the short-circuit breaking capacity of the branch breaks of the combined high-voltage DC circuit breaker, meeting the equivalence requirements of current and voltage parameters under actual operating conditions.

Description

Technical Field

[0001] This invention belongs to the field of high voltage testing technology, and specifically relates to a test circuit and method for breaking short circuits in a branch of a high voltage DC circuit breaker. Background Technology

[0002] Multi-terminal flexible high-voltage direct current (HVDC) transmission networks possess characteristics such as reliability, economy, and flexibility, enabling the transmission and consumption of large-scale renewable energy and providing strong technical support for the integration of renewable energy and the complementarity of various energy forms. However, the development and construction of flexible DC grids have been constrained by the limitations and high cost of DC circuit breaker technology applicable to HVDC systems. Combined HVDC circuit breakers can serve as core equipment for the future construction of multi-terminal flexible DC transmission networks, addressing these technical and cost constraints.

[0003] Combined DC circuit breakers play a dual role of control and protection in multi-terminal high-voltage direct current transmission systems. When a short-circuit fault occurs, the circuit breaker needs to interrupt and isolate the fault within 3–5 milliseconds, fundamentally limiting the rapid increase of short-circuit current and the expansion of the fault. From research and design to engineering application, combined DC circuit breakers must undergo type testing for verification, with the short-circuit breaking test being the most stringent sub-test.

[0004] Referring to the short-circuit breaking test conditions of high-voltage AC circuit breakers, the short-circuit breaking test of DC circuit breakers also requires equivalence in terms of short-circuit current amplitude and rate of rise during the high-current phase, current and voltage change rates during the commutation phase, and transient recovery voltage (TRV) parameters and energy equivalence of energy-consuming branches during the high-voltage phase. Currently, test stations mostly use small-capacity LC oscillating circuits to simulate the current and TRV parameters of the DC breaking process. Due to the limitation of capacitor capacity, it is difficult to meet the equivalence of the test parameters in the above three stages. In view of this, designing and developing a test circuit with high equivalence can effectively verify the breaking performance of the disconnecting branches of the combined DC circuit breaker. Summary of the Invention

[0005] The purpose of this invention is to provide a test circuit and method for short-circuit breaking of a branch circuit of a high-voltage DC circuit breaker. This circuit can assess the short-circuit breaking capacity of the branch circuit of a combined high-voltage DC circuit breaker, and meets the equivalence requirements of current and voltage parameters in actual operating conditions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A short-circuit breaking test circuit for a high-voltage DC circuit breaker includes a current source circuit, a voltage source circuit, and a converter branch;

[0008] The current source circuit consists of an impulse generator G, a closing switch MK, an auxiliary switch FK, a current-limiting reactor L, and a short-circuit test transformer T. The output terminal of the impulse generator G is connected in sequence to the closing switch MK, the current-limiting reactor L, the short-circuit test transformer T, and the auxiliary switch FK. The low-voltage side input terminal of the short-circuit test transformer T is connected to the impulse generator G. The high-voltage side output terminal of the short-circuit test transformer T is connected to the auxiliary switch FK.

[0009] The voltage source circuit includes a pulse main capacitor C. h High-voltage ignition ball gap Gap, and frequency modulation reactor L h ; Frequency modulation reactor L h One end is connected to the auxiliary switch FK, and the other end is connected to the high-voltage ignition ball gap Gap and the pulse main capacitor C. h Connected in series;

[0010] The commutation branch includes a pulse capacitor C. S High-frequency reactor L S The converter switch S is connected at one end to the auxiliary switch FK and at the other end to the common ground terminal.

[0011] The surge arrester energy dissipation branch is connected in parallel with the high-voltage side of the short-circuit test transformer T;

[0012] The DC circuit breaker under test, To, is connected in parallel with the high-voltage side of the short-circuit test transformer T and is grounded.

[0013] As a further improvement of the present invention, the current source circuit impulse generator G provides a low-frequency short-circuit test current of 20-50Hz.

[0014] As a further improvement of the present invention, it also includes a frequency modulation capacitor C0 and a frequency modulation resistor R0, wherein the frequency modulation capacitor C0 and the frequency modulation resistor R0 are connected in series and then connected in parallel with the high-voltage side of the short-circuit test transformer T.

[0015] As a further improvement of the present invention, the insulation coordination level of the high-voltage side of the transformer can withstand the transient overvoltage applied by the converter branch, and the overvoltage coordination coefficient of the high-voltage side is not less than 1.4.

[0016] As a further improvement of the present invention, the converter branch and surge arrester are components of the test circuit or parts of the DC circuit breaker under test.

[0017] A test method for a high-voltage DC circuit breaker branch short-circuit breaking test circuit includes:

[0018] S1. Test circuit parameter settings;

[0019] S2. Switching action timing control and data waveform analysis:

[0020] 1) At time 0, the closing switch MK opens, the auxiliary switch FK closes, the DC circuit breaker under test To closes, and the converter switch S and the high-voltage ignition ball gap GP are ready to be triggered.

[0021] 2) At time t1, the closing switch MK closes the short-circuit current, and the current source circuit provides the test current I to flow through the DC circuit breaker under test To;

[0022] 3) At time t2, the tested DC circuit breaker To of the fast-break mechanism of the branch circuit is activated and tripped, and arcing begins at the break point, forming a DC arc;

[0023] 4) At time t3, the converter switch S triggers the conductor; high-frequency current I... C This is superimposed on the arc current, forming an artificial zero-crossing point; after the current crosses zero and is interrupted, the commutator branch and the current source circuit oscillate, applying a first-stage transient recovery voltage U to the contacts of the DC circuit breaker under test, To. r ;

[0024] 5) At time t4, the auxiliary switch FK contacts form a certain opening distance, interrupting the oscillating high-frequency current, cutting off the current source circuit, and forming an isolation break.

[0025] 6) At time t5, the high-voltage ignition ball gap Gap triggers conduction, and the main capacitor C... h For frequency modulation reactor L h The voltage is discharged from the converter branch and superimposed on the transient voltage of the converter branch. The break point bears the peak value of the transient recovery voltage in the second stage.

[0026] 7) When the surge arrester's energy dissipation branch operates, the current flowing through the surge arrester is I. MOV The voltage source circuit is disconnected by the surge arrester discharging energy.

[0027] As a further improvement of the present invention, the test current I passes through the current-limiting reactor L and the short-circuit impedance L of the test transformer. T To adjust the rate of rise of the test current. This is achieved by adjusting the asymmetry of the short-circuit current through phase-selective closing of the closing switch MK; current amplitude I and rate of rise. for:

[0028]

[0029] In the formula, U G Let X0 be the rated voltage of the impulse generator, X0 be the inherent impedance of the generator system, and ω be the low-frequency angular frequency. The phase angle for phase selection and closing is τ, which is the DC time constant of the current source circuit.

[0030] As a further improvement of the present invention, during the opening of the DC circuit breaker under test, and at the expected moment, the converter switch S is turned on, and the pulse capacitor C... S and high-frequency reactor L S A high-frequency oscillating current is generated and applied to the contacts of the DC circuit breaker under test. After the DC circuit breaker under test is interrupted, the contacts are subjected to the first stage of transient recovery voltage, which is generated by the electromagnetic transient process of the commutation branch and the current source circuit.

[0031] As a further improvement of the present invention, the capacitor C S and reactor L S The amplitude of the current generated by the oscillation I h and frequency f h for:

[0032]

[0033] In the formula, U Cs The charging voltage of the capacitor, I h ≥1.6I, f h The range is from 4000 to 8000 Hz.

[0034] As a further improvement of the present invention, the main capacitor C h As a voltage source, after the auxiliary switch FK is turned off, the high-voltage ignition ball gap Gap quickly conducts, and the main capacitor C... h For frequency modulation reactor L h The voltage is discharged from the converter branch and superimposed on the transient voltage of the converter branch. The break point bears the peak value of the transient recovery voltage in the second stage.

[0035] During the process of the DC circuit breaker under test being subjected to the second-stage transient recovery voltage between the contacts, when the overvoltage reaches the test requirement value, the surge arrester operates, and the voltage source circuit is eventually disconnected by the surge arrester dissipating energy.

[0036] The auxiliary switch FK disconnects the current source circuit after the DC circuit breaker under test interrupts the short-circuit current and forms an isolation break between the current source circuit and the voltage source circuit.

[0037] Compared with the prior art, the present invention has at least the following technical effects:

[0038] This invention discloses a short-circuit breaking test circuit for a high-voltage DC circuit breaker, comprising a current source circuit, a converter branch, and a voltage source circuit. The current source circuit consists of an impulse generator G from a high-power test station, a closing switch MK, an auxiliary switch FK, a current-limiting reactor L, and a short-circuit test transformer T. The converter branch is a pulse capacitor C. S High-frequency reactor L SIt consists of a converter switch S. The voltage source circuit consists of a pulse main capacitor C. h High-voltage ignition ball gap Gap, and frequency modulation reactor L h Composition. During the test, a low-frequency short-circuit test current is provided by an impulse generator G, and the current amplitude I and rate of rise are satisfied. As required, after the tested DC circuit breaker breaks, the first-stage transient recovery voltage between the breaks is generated by the electromagnetic transient process of the converter branch and the current source circuit. The second-stage transient recovery voltage is generated by the oscillating discharge of the voltage source circuit. Finally, the surge arrester operates, and the voltage source circuit is disconnected by the energy discharged by the surge arrester. This circuit can be used to test the short-circuit breaking capacity of the breaking branch of the combined high-voltage DC circuit breaker, meeting the equivalence requirements of current and voltage parameters under actual operating conditions. Attached Figure Description

[0039] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. In the drawings:

[0040] Figure 1 This is the circuit diagram of the short-circuit breaking test synthesis circuit of the present invention;

[0041] Figure 2 This is the timing control diagram for the short-circuit breaking test of the present invention;

[0042] Figure 3 The waveform diagram is shown in the simulation calculation of the short-circuit breaking test of this invention. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0044] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0046] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0047] As attached Figure 1 As shown, a high-voltage DC circuit breaker branch short-circuit breaking test circuit includes a current source circuit, a voltage source circuit, and a converter branch.

[0048] The current source circuit consists of an impulse generator G, a closing switch MK, an auxiliary switch FK, a current-limiting reactor L, and a short-circuit test transformer T. The output terminal of the impulse generator G is connected in sequence to the closing switch MK, the current-limiting reactor L, the short-circuit test transformer T, and the auxiliary switch FK. The low-voltage side input terminal of the short-circuit test transformer T is connected to the impulse generator G. The high-voltage side output terminal of the short-circuit test transformer T is connected to the auxiliary switch FK.

[0049] The voltage source circuit includes a pulse main capacitor C. h High-voltage ignition ball gap Gap, and frequency modulation reactor L h ; Frequency modulation reactor L h One end is connected to the auxiliary switch FK, and the other end is connected to the high-voltage ignition ball gap Gap and the pulse main capacitor C. h Connected in series;

[0050] The commutation branch includes the pulse capacitor C. S High-frequency reactor L S The converter switch S is connected at one end to the auxiliary switch FK and at the other end to the grounding common terminal.

[0051] The surge arrester energy dissipation branch is connected in parallel with the high-voltage side of the short-circuit test transformer T;

[0052] The DC circuit breaker under test, To, is connected in parallel with the high-voltage side of the short-circuit test transformer T and is grounded.

[0053] Furthermore, it also includes a frequency modulation capacitor C0 and a frequency modulation resistor R0, which are connected in series and then in parallel with the high-voltage side of the short-circuit test transformer T.

[0054] During the test, a low-frequency short-circuit test current is provided by the impulse generator G, and the current amplitude I and rate of rise are satisfied. As required, after the DC circuit breaker under test is opened, the first stage transient recovery voltage between the breaks is generated by the electromagnetic transient process of the converter branch and the current source circuit, the second stage transient recovery voltage is generated by the oscillating discharge of the voltage source circuit, and finally the surge arrester operates, and the voltage source circuit is disconnected by the surge arrester discharging energy.

[0055] The current source circuit impulse generator G provides a low-frequency short-circuit test current of 20-50Hz, satisfying the test current amplitude I and rate of rise. The requirements are as follows: The current source circuit closing switch MK selects the phase for short-circuit closing, connecting the current source circuit and the DC circuit breaker under test. The current source circuit auxiliary switch FK disconnects the current source circuit after the DC circuit breaker under test interrupts the short-circuit current, forming an isolation gap between the current source circuit and the voltage source circuit. The low-voltage side of the current source circuit short-circuit test transformer T is the generator side, and the high-voltage side is the test object side.

[0056] A further improvement of this invention is that the short-circuit test transformer T mainly functions as an isolation transformer to protect the generator system on the low-voltage side of the transformer. During the time interval between the opening of the DC circuit breaker under test and the opening of the auxiliary switch FK, the insulation coordination level on the high-voltage side of the transformer can withstand the transient overvoltage applied by the converter branch, and the overvoltage coordination coefficient on the high-voltage side is not less than 1.4.

[0057] A further improvement of this invention is that when the converter branch and surge arrester are components of the test circuit, only the breaking branch of the DC circuit breaker under test can be tested. When the converter branch and surge arrester are components of the DC circuit breaker under test, the entire DC circuit breaker under test can be tested.

[0058] This invention also provides a test method for a high-voltage DC circuit breaker branch short-circuit breaking test circuit, comprising:

[0059] S1. Test circuit parameter settings;

[0060] S2. Switching action timing control and data waveform analysis:

[0061] 1) At time 0, the closing switch MK opens, the auxiliary switch FK closes, the DC circuit breaker under test To closes, and the converter switch S and the high-voltage ignition ball gap GP are ready to be triggered.

[0062] 2) At time t1, the closing switch MK closes the short-circuit current, and the current source circuit provides the test current I to flow through the DC circuit breaker under test To;

[0063] 3) At time t2, the tested DC circuit breaker To of the fast-break mechanism of the branch circuit is activated and tripped, and arcing begins at the break point, forming a DC arc;

[0064] 4) At time t3, the converter switch S triggers the conductor; high-frequency current I... C This is superimposed on the arc current, forming an artificial zero-crossing point; after the current crosses zero and is interrupted, the commutator branch and the current source circuit oscillate, applying a first-stage transient recovery voltage U to the contacts of the DC circuit breaker under test, To. r ;

[0065] 5) At time t4, the auxiliary switch FK contacts form a certain opening distance, interrupting the oscillating high-frequency current, cutting off the current source circuit, and forming an isolation break.

[0066] 6) At time t5, the high-voltage ignition ball gap Gap triggers conduction, and the main capacitor C... h For frequency modulation reactor L h The voltage is discharged from the converter branch and superimposed on the transient voltage of the converter branch. The break point bears the peak value of the transient recovery voltage in the second stage.

[0067] 7) When the surge arrester's energy dissipation branch operates, the current flowing through the surge arrester is I. MOV The voltage source circuit is disconnected by the surge arrester discharging energy.

[0068] A further improvement of the present invention is that: the test current amplitude I is controlled by the current-limiting reactor L and the short-circuit impedance L of the test transformer. T To adjust the rate of rise of the test current. This is achieved by adjusting the asymmetry of the short-circuit current through phase-selective closing of the closing switch MK. Specifically, this involves adjusting the current amplitude I and the rate of rise. for:

[0069]

[0070] In the formula, U G Let X0 be the rated voltage of the impulse generator, X0 be the inherent impedance of the generator system, and ω be the low-frequency angular frequency. The phase angle for phase selection and closing is τ, which is the DC time constant of the current source circuit.

[0071] During the tripping process of the DC circuit breaker under test, and at the expected moment, the converter switch S is turned on, and the pulse capacitor C... S and high-frequency reactor L S A high-frequency oscillating current is generated and applied to the contacts of the DC circuit breaker under test. After the DC circuit breaker under test breaks, the contacts experience a first-stage transient recovery voltage, which is generated by the electromagnetic transient processes of the commutation branch and the current source circuit.

[0072] A further improvement of the present invention is that: the capacitor C S and reactor L S The amplitude of the current generated by the oscillation I h and frequency fh for:

[0073]

[0074] In the formula, U Cs The charging voltage of the capacitor, I h ≥1.6I, f h The range is from 4000 to 8000 Hz.

[0075] I h The value of f is not less than the short-circuit current amplitude I. h The range is from 4000 to 8000 Hz.

[0076] The main capacitor C of the voltage source circuit h As a voltage source, after the auxiliary switch FK is turned off, the high-voltage ignition ball gap Gap quickly conducts, and the main capacitor C... h For frequency modulation reactor L h The voltage is discharged from the converter branch and superimposed on the transient voltage of the converter branch. The break point bears the peak value of the transient recovery voltage in the second stage.

[0077] A further improvement of the present invention is that: during the process of the DC circuit breaker under test being subjected to the second stage transient recovery voltage between the contacts, when the overvoltage reaches the test requirement value, the surge arrester operates, and the voltage source circuit is finally disconnected by the surge arrester dissipating energy.

[0078] Combination Figure 1 The circuit diagram of the test circuit shown is used for... Figure 2 The timing control diagram shown demonstrates the short-circuit breaking test of the disconnected branch of the combined high-voltage DC circuit breaker. The test parameters for the disconnected branch are: rated voltage 110kV, transient recovery voltage between the disconnect points 150kV, and short-circuit current rising to 10kA at converter switch S (i.e., I = 10kA). ), restore voltage rise rate The specific implementation method is as follows:

[0079] S1. Test circuit parameter settings, including the following parameters:

[0080] 1.1) The current source circuit impulse generator G is set to output voltage of 14kV and frequency of 50Hz. The equivalent current limiting reactor L of the circuit is 0.095Ω.

[0081] 1.2) The transformer ratio of the test transformer is 14kV / 42kV, and the equivalent short-circuit impedance is 15mΩ.

[0082] 1.3) Converter branch capacitor C S The current is 21μF, the charging voltage is 25kV, and the reactor L... S It is 33.4 μH.

[0083] 1.4) Main capacitor C of the voltage source circuit h The voltage is 200μF, the charging voltage is 165kV, and the frequency modulation reactor L... h It is 0.5mH.

[0084] S2. Switching action timing control and data waveform analysis:

[0085] 2.1) At time 0, i.e., the initial state. The closing switch MK is open, the auxiliary switch FK is closed, the DC circuit breaker under test To is closed, and the converter switch S and the high-voltage ignition ball gap GP are ready to be triggered.

[0086] 2.2) At time t1 (5ms), the closing switch MK closes the short-circuit current, and the current source circuit provides the test current I flowing through the DC circuit breaker under test, To. The expected instantaneous current at the 8m converter switch S is 10.4kA.

[0087] 2.3) At time t2 (6.5ms), the tested DC circuit breaker To of the fast-break mechanism of the branch circuit is activated and tripped, and the break point begins to arc, forming a DC arc.

[0088] 2.4) At time t3 (8ms), the converter switch S trigger conductor oscillates, generating a high-frequency current with an amplitude of 20kA and a frequency of 6012Hz. The high-frequency current I... C This current is superimposed on the arc current, creating an artificial zero-crossing point and establishing the conditions for interruption. After the current crosses zero and interrupts, the commutator branch and the current source circuit oscillate, applying a first-stage transient recovery voltage U to the contacts of the tested DC circuit breaker To. r U r The peak value is 160kV. It is 0.51 kV / μs.

[0089] 2.5) At time t4 (8.5ms), the auxiliary switch FK contacts form a certain opening distance, interrupting the oscillating high-frequency current, cutting off the current source circuit, and forming an isolation break.

[0090] 2.6) At time t5 (9.3ms), the high-voltage ignition ball gap Gap triggers conduction, and the main capacitor C... h For frequency modulation reactor L h The voltage is discharged from the converter branch and superimposed on the transient voltage of the converter branch. The break point bears the peak value of the transient recovery voltage in the second stage.

[0091] 2.7) When the surge arrester's energy-dissipating branch operates, the current flowing through the surge arrester is I. MOV The voltage source circuit is disconnected by the surge arrester discharging energy.

[0092] Combination Figure 3The obtainable experimental parameters are: I = 10.4 kA. U r The peak value is 160kV. The value was 0.51 kV / μs, and the experimental parameters met the expected requirements.

[0093] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of this teaching should not be determined by reference to the foregoing description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

[0094] The above content provides a further detailed description of the present invention. It should not be construed that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection of the present invention as defined by the submitted claims.

Claims

1. A test method for a high-voltage DC circuit breaker branch short-circuit breaking test circuit, characterized in that, The test circuit includes a current source circuit, a voltage source circuit, and a commutation branch; In the current source circuit, the output terminal of the impulse generator G is connected in sequence to the closing switch MK, the current limiting reactor L, the short-circuit test transformer T, and the auxiliary switch FK. The low-voltage side input terminal of the short-circuit test transformer T is connected to the impulse generator G, and the high-voltage side output terminal of the short-circuit test transformer T is connected to the auxiliary switch FK. In the voltage source circuit, the frequency-modulated reactor One end is connected to the auxiliary switch FK, and the other end is connected to the high-voltage ignition ball gap Gap and the pulse main capacitor. Connected in series; In the converter branch, one end of the converter switch S is connected to the auxiliary switch FK, and the other end is connected in sequence to the pulse capacitor. and high frequency reactor pulse capacitor The other end is grounded; One end of the surge arrester's energy dissipation branch is connected to the auxiliary switch FK, and the other end is grounded; the DC circuit breaker under test To is connected to the auxiliary switch FK, and the other end is grounded. The aforementioned test method includes: S1. Test circuit parameter settings; S2. Switch action timing control and data waveform analysis: 1) At time 0, the closing switch MK opens, the auxiliary switch FK closes, the DC circuit breaker under test To closes, and the converter switch S and the high-voltage ignition ball gap GP are ready to be triggered. 2) At time t1, the closing switch MK closes the short-circuit current, and the current source circuit provides the test current. The current flows through the DC circuit breaker under test, To; 3) At time t2, the fast-acting mechanism of the disconnecting branch causes the tested DC circuit breaker To to trip, and the break begins to arc, forming a DC arc; 4) At time t3, during the opening process of the tested DC circuit breaker To, the converter switch S is triggered to conduct; the pulse capacitor... and high frequency reactor The high-frequency oscillating current is superimposed on the arc current, forming an artificial zero-crossing point. After the current crosses zero and is interrupted, the commutator branch and the current source circuit oscillate, applying a first-stage transient recovery voltage to the contacts of the DC circuit breaker under test (To). The transient recovery voltage is generated by the electromagnetic transient process of the commutation branch and the current source circuit; 5) At time t4, the auxiliary switch FK contacts form a certain opening distance to interrupt the oscillating high-frequency current. The auxiliary switch FK cuts off the current source circuit after the DC circuit breaker under test interrupts the short-circuit current and forms an isolation break between the current source circuit and the voltage source circuit. 6) At time t5, the high-voltage ignition ball gap triggers conduction, and the main capacitor... For frequency modulation reactor The discharge voltage is superimposed on the transient voltage of the converter branch, and the test DC circuit breaker To experiences the peak value of the transient recovery voltage in the second stage between the contacts. 7) During the process of the DC circuit breaker under test being subjected to the second-stage transient recovery voltage between its contacts, when the overvoltage reaches the test requirement value, the surge arrester's energy-dissipating branch trips, and the current flowing through the surge arrester is: The voltage source circuit is disconnected by the surge arrester discharging energy.

2. The test method for the branch short-circuit breaking test circuit of the high-voltage DC circuit breaker according to claim 1, characterized in that: The test current Through current-limiting reactor and the short-circuit impedance of the test transformer To adjust the rate of rise of the test current. This is achieved by adjusting the asymmetry of the short-circuit current through the phase-selective closing of the closing switch MK; current amplitude and rate of increase for: In the formula, To compensate for the rated voltage of the generator. The inherent impedance of the generator system, It is a low-frequency angular frequency. To select the closing phase angle, is the DC time constant of the current source circuit.

3. The test method for the branch short-circuit breaking test circuit of the high-voltage DC circuit breaker according to claim 2, characterized in that: The capacitor and reactor Current amplitude generated by oscillation and frequency for: In the formula, The charging voltage for the capacitor. , The range is from 4000 to 8000 Hz.

4. The test method for the branch short-circuit breaking test circuit of the high-voltage DC circuit breaker according to claim 1, characterized in that: The current source circuit impulse generator G provides a low-frequency short-circuit test current of 20~50Hz.

5. The test method for the branch short-circuit breaking test circuit of the high-voltage DC circuit breaker according to claim 1, characterized in that: The test circuit also includes a frequency modulation capacitor C0 and a frequency modulation resistor R0, which are connected in series and then in parallel with the DC circuit breaker under test To.

6. The test method for the branch short-circuit breaking test circuit of the high-voltage DC circuit breaker according to claim 1, characterized in that: The insulation coordination level of the high-voltage side of the transformer can withstand the transient overvoltage applied by the converter branch, and the overvoltage coordination coefficient of the high-voltage side is not less than 1.

4.

7. The test method for the short-circuit breaking test circuit of a high-voltage DC circuit breaker according to any one of claims 1 to 6, characterized in that: The converter branch and surge arrester are components of the test circuit or parts of the DC circuit breaker under test.

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